1. Technical Field
The present device is a support surface with a layer of heat tubes, and/or an upper thermal layer comprising a gel or viscous fluid carrier and phase change material, which resist warming of the support surface, and reduce the likelihood of ulceration and/or promote the healing of bedsores.
2. Background Information
Bedsores, or decubitus ulcers, can be a serious problem in bedridden or wheelchair-bound patients, particularly for people who are paralyzed, emaciated, post-surgical, elderly, emaciated, or diabetic. Bedsores are a common and persistent problem for those who have to spend a great deal of time in bed, and for their physicians and nurses. As baby boomers age, the elderly population increases, and the ordinary bedsore becomes more of a problem. People with casts or splints can also develop bedsores. Bedsores can penetrate to the muscles and bone and are surprisingly life-threatening on occasion. Where, for example, a geriatric patient in a fetal position develops bedsores between his knees, one or more of the bedsores can become gangrenous and necessitate amputation of a limb. A bedsore can progress to necrosis, septic arthritis, pathologic fracture, and septicemia.
To avoid bedsores, nurses or nurse assistants turn patients at prescribed intervals, inspect their skin and apply creams, give massages and baths to patients, exercise limbs, and promptly change wet bed sheets and bedclothes. Patients are placed on air-filled mattresses, sponge rubber xe2x80x9cegg cratexe2x80x9d mattresses, silicone gel or water mattresses, mattresses filled with fluid or tiny spheres, or Stryker turning mattresses. Protective padding, such as sheepskin or pillows, is placed on bony prominences under braces, casts, etc. Topical ointments, dressings, debridement, and antibiotics are prescribed to curb infections in decubitus ulcers. Prevention and management of bedsores is nevertheless difficult, and further assistance is needed.
Bedsores are ordinarily developed over the bony prominences of the body, such as the heels, sacrum (tailbone), ischia, greater trochanters, and ankles (external malleoli). It has been found that bedsores are less likely to form where the skin above the bony prominences is maintained at a slightly cooler temperature than normal skin temperature. The normal core temperature (xe2x80x9cnormothermiaxe2x80x9d) of the human body is between 36xc2x0 and 38xc2x0 C. Skin temperature typically ranges between about 32xc2x0 C. and about 38xc2x0 C., depending on ambient temperature, the amount and type of clothing being worn, the core temperature, and where the skin is located on the body. On a typical mattress, seat cushion, inside a prosthesis, etc., heat is trapped between the body and the covered skin surface and the skin temperature rises rapidly to and is maintained at between about 36 and 38 degrees C. It is believed that skin temperatures in this range promote soft tissue breakdown by increasing tissue metabolism, promoting local perspiration, which wets and weakens the stratum corneum (surface layer of the skin), and increasing friction and shear forces between the sweaty skin and the bedding and/or clothes between the skin and the support surface.
The support surface of the present invention focuses xe2x80x9crelative coolingxe2x80x9d, or cooling of the skin relative to the temperatures the skin would reach on a conventional mattress, under the bony prominences, where bedsores are more likely to form. Relative cooling is accomplished in the present invention with an envelope containing phase change material distributed in a gel or viscous fluid carrier. Cooling is held to a narrow temperature range just below normal skin temperature, since cold temperatures are uncomfortable and undesirable, particularly where the patient is emaciated or otherwise infirm. The present invention both reduces the likelihood of bedsore formation, and aids in the healing of early stage bedsores that have already formed.
A support surface herein for comfort, or reducing the incidence and promoting the healing of bedsores, includes:
(a) at least one thermal layer comprising: a phase change material having a melting point of between about 18 and 32 degrees Centigrade; a gel or viscous fluid carrier in which the phase change material is substantially evenly distributed; and a fluid-impermeable, conformable envelope surrounding the phase change material and the carrier;
(b) at least one conformable compression support layer beneath and adjacent to the thermal layer;
(c) at least one conformable base support layer beneath and adjacent to the compression layer, the base support layer having a higher ILD than the compression layer;
wherein the layers are joined within an outer covering.
The support surface can also be used simply for delaying warming of the surface of the skin in contact with the support surface. A support surface pad or the like herein includes:
(a) phase change material having a melting point of between about 18 and 32 degrees Centigrade;
(b) a gel or viscous fluid carrier in which the phase change material is substantially evenly distributed; and
(c) a fluid-impermeable, conformable envelope surrounding the phase change material and the carrier.
This support surface, which is preferably a mattress, support pad, or seat cushion, includes phase change materials just beneath its upper surface. Phase change materials for use herein are preferably encapsulated, and have a phase change such that temperatures between 18xc2x0 and 33xc2x0 C. will be delivered to the skin. A preferred embodiment of the support surface includes a heat tube layer for channeling heat from the warmer areas of the support surface to the cooler areas, or from the warmer areas of the body to the cooler skin regions, such as the extremities (e.g., ankles and heels). By maintaining the skin temperature below the levels typically recorded on a conventional foam mattress, the body is kept more comfortable, and the risk of developing bedsores and the like is greatly reduced. This inexpensive, easy to use support surface maintains a temperature within a prescribed range for a sufficient period of time to reduce the likelihood of ulceration and promote healing, when used in the prescribed manner.
A support surface herein alternatively includes:
(a) at least one heat tube layer comprising at least two adjacent heat tubes, at least one of the heat tubes containing a refrigerant liquid, the refrigerant liquid having a boiling point between about 80 and about 85 degrees Fahrenheit;
(b) at least one conformable compression support layer beneath and adjacent to the heat tube layer; and
(c) at least one conformable base support layer beneath and adjacent to the compression layer, the base support layer having a higher ILD than the compression layer;
wherein the layers are joined within an outer covering.